Electrode connector

ABSTRACT

A connector for use with a tab style biomedical electrode is disclosed. The connector comprises pivotally mounted movable and fixed jaws and a spring biasing the jaws toward a closed position. The connector provides a high tab release force and yet provides an acceptably low actuation force. Preferably, the fixed jaw includes a smooth, continuous surface which facilitates insertion of the tab between the jaws of the connector.

This is a continuation of U.S. patent application Ser. No. 07/990,692,filed Dec. 15, 1992, and issued as U.S Pat. No. 5,407,368 on Apr. 18,1995.

THE FIELD OF INVENTION

The present invention relates to connectors for biomedical electrodeshaving an electrically conductive contacting tab with generally flatupper and lower surfaces.

BACKGROUND

The art is replete with different types of biomedical electrodes whichhave an electrically conductive contacting tab. Examples of suchbiomedical electrodes are described in U.S. Pat. Nos. 4,543,958 toCartmel, 4,798,208 to Faasse, Jr., 5,012,810 to Strand et al., 5,078,138to Strand et al., 5,078,139 to Strand et al., 5,133,356 to Bryan et al.,and U.S. patent application Ser. No. 07/686,049, the entire contents ofeach of which are herein expressly incorporated by reference. Particularexamples of such electrodes include 3M Red Dot™ ECG and EKG electrodesgenerally available from the Minnesota Mining and Manufacturing Co. (3M)of St. Paul, Minn. Typically, such electrodes have a substantially flatconstruction which leads to significant advantages including: (1) suchan electrode is less conspicuous when worn under a patient's clothes andless obstructive to other medical procedures, and (2) the low profile oftab-style electrodes provides a structure which is free of anysubstantial projections that might cause discomfort for a patient shouldthe patient be bumped in the vicinity of the electrode or should thepatient lie down on the electrode.

The art is also replete with connectors for electrically connectingmedical equipment to a tab-style electrode. For example such medicalequipment may comprise electrical receiving instrumentation, diagnosticequipment, stress monitoring equipment or other testing equipment fordetecting a patient's electrical signals. Other examples of medicalequipment include therapeutic electrical instrumentation such astranscutaneous electronic nerve stimulation (TENS) devices used for painmanagement and neuromuscular stimulation (NMS) equipment used fortreating conditions such as scoliosis. Such medical equipment may alsoinclude the equipment used in electrosurgery or equipment used withdefibrillation pads for emergency cardiac treatment.

Examples of connectors for connecting medical equipment to a tab-stylebiomedical electrode include U.S. Pat. Nos. 4,061,408 to Bast et al.,4,555,155 to Drake, 4,700,997 to Strand, 4,842,558 to Strand, and4,952,177 to Drake et al.

The art also includes "alligator" type electrical connectors. An"alligator" type electrical connector typically includes a fixed jaw anda movable jaw, a pin for mounting the movable jaw for pivotal movementrelative to the fixed jaw between tab accept and closed positions and aspring for biasing the movable jaw toward the closed position. Aleadwire is typically fixedly connected to the fixed jaw so that thefixed jaw does not move relative to the leadwire. As used herein, theterm "fixed jaw" when used to describe one of the jaws of an "alligator"type connector, means that jaw which remains stationary or fixedrelative to the leadwire when the connector is opened. Particularexamples of "alligator" type electrical connectors include U.S. Pat.Nos. 3,090,029 to Stroebel, 3,644,877 to Carbonneau, 4,797,125 toMalana, 4,702,256 to Robinson et al., and 5,058,589 to Ding et al.

Prior art "alligator" type electrical connectors suffer from manydrawbacks. In order to ensure a very high pull off force of theconnector from the tab, some prior art "alligator" type electricalconnectors include a very strong spring which renders the electricalconnector difficult to open. Also, some prior art electrical connectorsinclude a hole, depression, groove, slot, slit or other discontinuoussurface in a jaw which is designed to deflect the tab of the electrode.Such deflection of the tab generally results in a higher grasping forcefor the tab but also tends to mar, puncture or otherwise damage theconductive surface of the electrically conductive contacting tab of thebiomedical electrode. Such damage may potentially result in a loss ofcontinuity or may otherwise adversely affect the electrical propertiesof the biomedical electrode.

Some jaws of prior art "alligator" electrical connectors include teeth,abutment surface, labyrinth-like or tortuous paths or an otherwise roughsurfaces. A rough surface may include a structure that substantiallydeforms or deflects the electrode contacting tab during insertion of thetab into the connector. Again, the deflection of the tab into a surfaceirregularity may increase the tab pull off force of the connector, butnot without costs. The rough surface may "catch" the electricallycontacting tab and cause the contacting tab to bend or otherwise deformwhile the tab is being inserted into the connector. Such action mayrender the electrical connector difficult to place on the tab of anelectrode.

Also, the V-shaped nature of many prior art "alligator" type connectorsrender them particularly susceptible to tangling with the leadwires ofother leadwires and connectors as the leadwire of one assembly mayeasily slip between proximal ends of the fixed and movable jaws ofanother assembly.

Finally, some existing prior art "alligator" type electrical connectorsmay be unsuitable for biomedical use as they have relatively sharpportions which may be uncomfortable for some patients. For example,should the patient roll on top of the connector, a sharp edge or toothmay cause discomfort for the patient.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a connector for a biomedical electrodehaving a generally flat, electrically conductive contacting tab. Theconnector comprises a fixed jaw having a tab engagement surface, amovable jaw having a tab engagement surface and a manually engagableactuation surface, a pivotable mounting mechanism for mounting themovable jaw for pivotable movement relative to the fixed jaw between thetab accept position and a close position, and a spring for biasing themovable jaw toward the closed position.

Preferably the fixed jaw comprises smooth, continuous tab engagement andlead-in surfaces, and the movable jaw comprises a tooth portion having atab engagement surface, and a smooth lead-in surface. The tooth portionpreferably comprises two teeth having a groove therebetween.

The present invention provides a connector which: 1) provides anactuation force less than about nine (9) pounds so that a broad range ofuser's may open the jaws of the connector while maintaining a desirabletab retention force, 2) preferably provides smooth tab engagementsurfaces on one jaw which restrict damage to the tab of the electrodeand which facilitate insertion of the tab between the jaws of theconnector, 3) preferably provides a jaw with a continuous tab engagementsurface to restrict excessive deflection of the tab of the electrodewhen it is clamped between the jaws of the connector to thereby restrictdamage to the tab of the electrode, 4) may be constructed from X-Raytranslucent materials, 5) is particularly suitable for use with atab-style electrode comprising a tab with a stiff-flexible layer and aflexible-deformable second layer, 6) restricts the likelihood that theconnector and its leadwire may become entangled with anotherconnector/leadwire assembly or itself, 7) presents a low-profile whichresults in numerous advantages including comfort for the patient, 8)includes grasping or "manually activation" surfaces which conform to theshape of a user's digits, and 9) is free of sharp surfaces that mightcause discomfort for a patient should the patient be bumped in thevicinity of the connector or should the patient lie down on theconnector.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will be further described with reference to theaccompanying drawing wherein like reference numerals refer to like partsin the several views, and wherein:

FIG. 1 is an exaggerated schematic view of portions of the electricallyconductive tab of one example of biomedical electrode for use with theconnector of the present invention;

FIG. 2 is a top view of a first embodiment of connector according to thepresent invention illustrating a portion of a leadwire;

FIG. 3 is a reduced sectional view of the connector of FIG. 2 takenapproximately along lines 3--3 of FIG. 2, but which illustrates anunsectioned spring, and which illustrates a fixed and movable jaw in aclosed position;

FIG. 4 is a reduced sectional view similar to FIG. 3 except that FIG. 4illustrates an electrically conductive tab of a biomedical electrodeclamped between the fixed and movable jaws;

FIG. 5 is a perspective view of the connector of FIG. 2 illustrating anelectrically conductive tab of a biomedical electrode clamped betweenthe fixed and movable jaws;

FIG. 6 is an enlarged front end view of the connector of FIG. 2illustrating fixed and movable jaws in a closed position;

FIG. 7 is a partial cross section view of a distal end of fixed andmovable jaws of a second embodiment of connector according to thepresent invention; and

FIG. 8 is a schematic illustration of the test equipment used to conducttab release and actuation force tests according to the presentinvention.

DETAILED DESCRIPTION

FIGS. 2 through 6 of the drawing show a first embodiment of connectoraccording to the present invention generally designated by the referencecharacter 10. The connector 10 is adapted for use with a biomedicalelectrode having an electrically conductive contacting tab.

Examples of suitable biomedical electrodes are found in U.S. Pat. Nos.4,543,958 to Cartmel, 4,798,208 to Faasse, Jr., 5,012,810 to Strand etal., 5,078,138 to Strand et al., 5,078,139 to Strand et al., 5,133,355to Strand et at.; 5,133,356 to Bryan et al., and U.S. patent applicationSer. No. 07/686,049, the entire contents of which are herein expresslyincorporated by reference. The connector 10 may be used with biomedicalelectrodes having widely varying thicknesses of electrically conductivetabs.

The connector 10 is particularly suitable for use with a biomedicalelectrode 14 having a firm, but flexible layer and a deformable layer.In particular, the biomedical electrode may comprise the electrodedescribed in U.S. Pat. No. 5,133,356 to Bryan et al. the entire contentsof which are herein expressly incorporated by reference.

FIG. 1 is a schematic illustration of a portion of the electricallyconductive contacting tab of a biomedical electrode 14 having a firm,but flexible layer 11 and a deformable layer 12. The material used toconstruct the firm, flexible layer 11 preferably is constructed from amaterial that resists substantial permanent plastic deformation underforces exerted by the jaws of a connector, and is compatible with knownprocesses for vapor coating silver. Such processes are used to coat asilver/silver chloride conductive coating 15 onto the layer 11.

Suitable materials for the layer 11 include, but are not limited toScotchpar brand 3 mil PET film, commercially available from theMinnesota Mining and Manufacturing Co. (3M) of St. Paul, Minn., apolyester film commercially available as "Melinex" 505-300, 329 or 339film from ICI Americas of Hopewell, Va. (coated with a silver/silverchloride ink commercially available as "R-300" ink from Ercon, Inc. ofWaltham, Mass.), or a web of polyester/cellulose fibers commerciallyavailable as "Manniweb" web from Lydall, Inc. of Troy, N.Y. (having acarbon ink commercially available as "SS24636" ink from Acheson ColloidsCompany of Port Huron, Mich.).

Preferably, the material used to construct layer 11 is a 3 mil (0.075mm) thick strip of polyethylene terephthalate film. The properties ofthe film included a tensile strength of about 28,000 psi in a machinedirection, approximately 35,000 psi in the transverse direction, both asmeasured according to ASTM D882A. The coefficient of dynamic friction ofthis film is about 0.5 as measured by ASTM D1894. The commercial sourceof this film is ICI Films of Wilmington, Del., branded as "Melinex" 505.

The deformable layer 12 should be substantially softer than the layer 11so that the layer 12 deforms in response to being clamped by the jaws ofthe connector 10. The deformable layer 12 enhances mechanical contactbetween the connector 10 and the electrode 14.

The layer 12 is adhered to the layer 11 by a layer of adhesive 16 suchas a conventional acrylate adhesive. The adhesive may comprise a layerof 95.5%/4.5% isooctyl acrylate/acrylic acid copolymer adhesive, coatedto a weight of 920 mg/200 cm² of backing area. However, any suitableadhesive may be utilized so long as the adhesive resists shear betweenthe layers 11 and 12 and is compatible with the materials used toconstruct the layers 11 and 12.

Suitable materials for the layer 12 include, but are not limited to, alow density polyethylene such as NA 964-226, commercially available fromQuantum Chemical of Rolling Meadows, Ill. This material may be extrudedinto a film with a thickness between about 0.002 to about 0.007 inches(0.005 to 0.013 cm), and preferably has a hardness of about 48 on theShore D scale when measured according to ASTM Standard D2240, and inselecting alternative materials, those having a hardness between about45 to 55 Shore D are believed to be particularly suitable. Thecommercial source of the layer 12 and adhesive 16 tape is MinnesotaMining and Manufacturing (3 M) Company, of St. Paul, Minn., branded as"Blenderm" tape.

Referring now to FIGS. 2 through 6 of the drawings, there is shown theconnector 10. The connector 10 comprises fixed 20 and movable 21 jaws,and a pivotal mounting means for mounting the movable jaw 21 for pivotalmovement relative to the fixed jaw 20 between a tab accept position withthe fixed jaw 20 spaced from the movable jaw 21 so that the tab of thebiomedical electrode (e.g. 14) may be received between the jaws 20 and21, and a closed position (FIG. 3) with fixed 20 and movable 21 jawsspaced more closely than in the tab accept position.

The movable jaw 21 comprises proximal and distal ends, a top surface 24and a bottom surface 25. The fixed jaw 20 comprises a bottom surface 27,proximal and distal end portions terminating in proximal and distal endswith the proximal end portion having a top surface 26. At the proximalend of the fixed jaw 20, the connector is adapted to be connected to aleadwire L having an outside diameter.

The connector 10 is elongate and has a longitudinal axis along itslength (preferably about 1.5 inches). The connector 10 has an overallheight (preferably about 0.38 inches, but should be less than about 1.5inches and more preferably less than about 0.5 inches) presenting a lowprofile connector and an overall width (preferably about 0.54 inches).The overall width is preferably at least 1.1 times greater than theoverall height of the connector. Providing a connector with an overallwidth that is greater than its height is believed to provide a connectorwith resists rolling about its longitudinal axis.

The connector 10 may optionally include various features which conformthe connector's operative surfaces to the general shape of a user'shand. For example, the bottom surface 27 of the fixed jaw 20 comprisesan arcuate portion for conforming to the shape of a user's digits. Forexample the arcuate portion may be arcuate about an axis that isperpendicular to the longitudinal axis of the connector 10 and may havea radius of curvature of about 1.25 inches. The vertical distance fromthe top of surface 27 in FIG. 3 to its bottom is preferably about 0.06inches.

The manually engagable actuation surface 32 may optionally include alocating means for assisting users in placing their digits in thedesired position on the movable jaw 21. The locating means may comprisea rib, detent, depression, groove or slot in the desired position on thetop surface 24 of the movable jaw 21.

The pivotal mounting means comprises a recess portion 18 recessed fromthe top surface 26 of the fixed jaw 20, and a pin 19 situated betweenthe proximal and distal ends of the movable jaw 21 so that the movablejaw 21 can pivot about the axis of the pin 19. Preferably, the pin 19may be integrally molded with the movable jaw 21 so that the pin andmovable jaw form one, monolithic piece. Alternatively, the pin maycomprise a metal pin adapted to be received in a slot in the movable jawand fixed jaw.

The pin 19 is adapted to be received in a pivot groove in the fixed jaw20 so that the movable jaw 21 can pivot about the axis of the pin 19when a user manually presses on actuation surface 32. As best seen inFIG. 4, the pin 19 is situated to allow the tab of the electrode to besituated directly between the pin 19 and the fixed jaw 20. When it issaid that the tab of the electrode is situated "directly between" thepin 19 and the fixed jaw 20, it is meant that, in FIG. 4, if a line isdrawn vertically through the pin 19 and jaw 20, it would intersect aportion of the electrode's tab. This feature of the present inventionaffords the use of the connector 10 for a variety of sizes of tabs andalso affords full insertion of the tab into the connector.

In the closed position (FIG. 3), the distance D between the top surface26 of the fixed jaw 20 and the bottom surface 25 of the movable jaw 21at the proximal end of the movable jaw 21 is less than the outsidediameter of the leadwire L. For example, the distance D may beapproximately 0.06 inches. This feature of the present inventionrestricts the chances that a leadwire L will become caught between themovable and fixed jaws of a connector, thereby restricting the chancesthat the connector 10 will become entangled with a leadwire L.

Another feature of the present invention that restricts the chances thatthe connector 10 will become entangled with a leadwire L is-that themovable jaw 21 comprises a cam surface C generally adjacent its proximalend (See FIGS. 3 and 4). As shown in FIG. 3, the cam surface C issituated at an acute angle (alpha) relative to the top surface 26 of thefixed jaw 20. Thus, it is believed that when a leadwire L comes intocontact with the cam surface C, the cam surface C will tend to move theleadwire L away from the recess portion 18 and away from becoming caughtbetween the movable jaw 21 and fixed jaw 20.

The connector 10 also includes a biasing means such as a coil spring 23for biasing the movable jaw 21 toward the closed position. While thebiasing means is shown as a coil spring, it should be noted that thebiasing means may comprise any suitable biasing means such as, but notlimited to a leaf spring, a leaf spring integrally molded into the fixedjaw, an elastomeric structure (e.g. an egg shaped elastomer between thefixed and movable jaws), or a torsion spring so long as the movable jawis biased toward the closed position. The coil spring may be constructedfrom any suitable material such as a plastic or metal. Optionally, thecoil spring may be constructed from a substantially X-ray translucentmaterial such as, Hytrel 5556 or Hytrell 7246 polyester elastomersgenerally available from DuPont of Delaware.

As shown in FIGS. 3 and 4, preferably the fixed jaw 20 has a smooth,continuous tab engagement surface 28; and the movable jaw 29 has a toothportion 30 with a tab engagement surface 31, and a manually engagableactuation surface 32. However, it should be noted that the position ofthe tooth portion and the smooth, continuous tab engagement surface maybe reversed, that is, the movable jaw may have a smooth, continuous tabengagement surface and the fixed jaw may have the tooth portion.

Both the movable jaw 21 and the fixed jaw 20 have a smooth lead-insurface 29. Preferably, the lead-in surfaces 29 are continuous,generally planar surfaces and form an angle therebetween of about 40degrees.

As used herein, when it is said that a surface is "smooth" surface (e.g.the tab engagement or lead-in surfaces), it is meant that theparticularly referenced surface is free of any rough surfaces such asteeth, cylindrically shaped terminal portions, abutment surfaces,labyrinth-like or tortuous paths, or otherwise rough surface that maysubstantially deform, bend or deflect an electrode contacting tab duringinsertion of the tab into the jaws of the connector. A "smooth" tabengagement surface or lead-in surface is preferably a generally planarsurface, but may comprise a slightly arcuate surface so long as thesurface does not present a structure that is likely to bend, deform orotherwise deflect the electrode tab upon its insertion between the jawsof the connector.

As used herein, when it is said that a surface is a "continuous" surface(e.g. a tab engagement surface), it is meant that the particularlyreferenced tab engagement surface is free of any discontinuities such asa hole, depression, groove, slot, slit or other discontinuous surfaceswhich tend to substantially deflect the conductive tab of the electrodewhen it is clamped between the jaws of the connector. Such deflectionmay mar, puncture or otherwise damage the conductive surface of theelectrically conductive contacting tab of the biomedical electrode thatmay potentially result in a loss of continuity or may otherwiseadversely affect the electrical properties of the biomedical electrode.The discontinuity may also substantially deform, bend or deflect anelectrode contacting tab during insertion of the tab into the jaws ofthe connector with the attendant disadvantages described above.

The fixed and movable jaws 20 and 21 comprise distal end portions havinggenerally arcuate surfaces terminating in distal ends. The arcuatesurfaces present blunt surfaces to a patient which reduces the chancesthat the connector will cause discomfort for the patient. The distal endof the movable jaw 21 is spaced proximally from the distal end of thefixed jaw 20.

In addition to the smooth lead-in surfaces 29, the connector 10 alsoincludes several features which further assist a user in placing the tabof the electrode between the fixed and movable jaws 20 and 21. Forexample, at each position along the longitudinal axis of the connector10, the fixed jaw 20 is wider than the movable jaw 21. When theconnector 10 is viewed from a top plane (as the connector is in FIG. 2),the distal end portion of the fixed jaw 20 encompasses the distal endportion of the movable jaw 21. In this view, a user can determine when atab is placed between the movable and fixed jaws 20 and 21 as, when atab is placed between the movable and fixed jaws, a portion of the fixedjaw 20 will no longer be seen as the tab will block a user's view. Inthis manner, the connector 10 is facilitates insertion of the tabbetween the jaws. Optionally, the movable jaw 21 may have a hole in itsdistal end portion for viewing the relative position of the tab of theelectrode and the jaws of the connector.

The tooth portion 30 preferably comprises a pair of teeth 33 as bestseen in FIG. 6. The teeth 33 have a groove 34 therebetween, and each ofthe teeth 33 have a tab engagement surface 31. The groove 34 is believedto be particularly desirable when the connector 10 is used with a tabhaving a deformable layer 12 (e.g. a tab similar to the tab shown inFIG. 1). It is believed that some of the material 12 may enter thegroove 34 and enhance the holding properties of the connector 10.

Each of the teeth 33 have a rear ridge surface 39. The rear ridgesurfaces 39 are preferably situated generally perpendicular relative toa horizontal line with reference to FIG. 3. A perpendicular rear ridgesurface tends to beneficially grasp the electrode tab, particularly whenthe electrode tab has a deformable layer such as the layer 12 shown inFIG. 1. At most, the ridge surfaces 39 should be inclined at an angle ofbetween more than about 60 degrees and less than about 120 degreesrelative to a horizontal line with reference to FIG. 3. If the angle isless than 60 degrees, the ridge surface 39 tends to act as a cammingsurface to open the jaws when an electrode 14 with a flexible layer(e.g. 12) is pulled longitudinally from the jaws of the connector,clearly an undesirable result. If the angle is more than 120 degrees,than the movable jaw 21 becomes difficult to construct as the shapebecomes complicated.

Preferably, the connector 10 has electrically conductive plates orplastic inserts 41 and 42 which place the distal end portion of thefixed jaw 20 in electrical contact with the leadwire L. For example, theconductive plates 41 and 42 may be injection molded of a conductivematerial such as, a 40 percent (%) carbon fiber reinforcedAcrylonitrile-Butadiene-Styrene material, sold under the name RTP 687generally available from RTP Co. of Winona Minn. (which is also asubstantially X-ray translucent material). Although they are shown astwo separate plates, the conductive plates 41 and 42 preferably comprisea single, monolithic conductive plate constructed from the samematerial. Preferably, the distal end of the fixed jaw 20 has a lipportion which helps retain the plates 41 and 42 in the fixed jaw 20.Gripping tabs 45 may be molded into fixed jaw 20 for the purpose ofgripping the leadwire L.

Also preferably, the movable jaw 21 and portions of the fixed jaw 20 areconstructed from a material which need not be an electrically conductivematerial (as long as the fixed jaw also includes conductive plasticinserts). Suitable materials includes plastics, metals and polymers.Preferably, the movable jaw 21 and portions of the fixed jaw 20 areconstructed from Delrin material generally available from DuPont (whichis substantially X-ray translucent). However, it should be pointed outthat, optionally, the movable jaw may be constructed from anelectrically conductive material such as the material used to constructconductive plastic inserts 41 and 42. Also optionally, the spring 23 maybe constructed from an electrically conductive material.

Referring now to FIG. 7 of the drawings, there is shown a secondembodiment of connector according to the present invention generallydesignated by reference character 100. The connector 100 includes manyfeatures that are generally identical to the connector 10 and which havebeen given the same reference character to which the suffix "A" has beenadded.

Unlike the connector 10, in the connector 100, the fixed jaw 20A, andmore particularly the conductive plate 41A has a recess 101 adapted toreceive the ridge of the tooth portion. Generally speaking, theconnector 100 is believed to exhibit a higher tab release force than theconnector 10. However, it is believed to be more difficult to insert atab of an electrode between the jaws 20A and 21A of the connector 100 asthe tab can be caught in the recess 101 and bent.

TEST RESULTS

A connector of the type described with reference to FIGS. 2 through 6was made as follows. The axis of the spring 23 was situatedapproximately 0.31 inches from the axis of the pin 19. The distancebetween the axis of the pin 19 and teeth 33 was approximately 0.22inches. The total surface area of the tab engagement surfaces of theteeth was approximately 0.016 square inches. The above describedconnector is hereafter referred to as Connector A.

Connector B comprises an alligator type clip number M306L10 generallyavailable from the Minnesota Mining and Manufacturing Co. (3M) of St.Paul, Minn. (or alternatively Hershman, of Germany). Connector Ccomprises an Alligator clip number J5 generally available from theMinnesota Mining and Manufacturing Co. (3M) of St. Paul, Minn. (oralternatively Hershman, of Germany). Connector D comprises an alligatortype clip number S106L10 generally available from the Minnesota Miningand Manufacturing Co. (3M) of St. Paul, Minn. or model No. 6A2A1A21generally available from Tronomed, Inc. of Laguna Hills, Calif.Connector E comprises a clip similar to the clip shown in U.S. Pat. No.4,797,125 believed to have been generally available from Tronomed, Inc.of Laguna Hills, Calif. Connector F comprises a DURALINC™ clip number2B2A1A21 generally available from Tronomed, Inc. of Laguna Hills, Calif.Connector G comprises an Astro-Trace™ clip believed generally availablefrom LeBlanc.

Actuation Force Measurements

FIG. 8 is a schematic illustration of test equipment used to recordactuation force measurements for the various connectors. The testequipment included a base 1, a digital force gauge 2 with jig 3, probe 4and readout 5.

A connector to be measured was placed on the base 1 with a double sidedadhesive tape A (optionally a clamp may be used) so that the movable jawM of the connector was accessible. The movable jaw of the connector wasthen depressed using a digital force gauge 2, held in jig 3 allowingprecision movement. In particular, the Model DFI-50 digital force gauge,commercially available from Chatilion, was used. The probe 4 of theforce gauge was manually situated so that it was centered against theuppermost point of the normal finger position for opening the connectorin the manner shown schematically in FIG. 8, and additional force wasapplied in a direction generally normal to the base 1. The forcerequired to open the connector to its widest normal position was notedon readout 5.

The widest normal position is defined herein as the position wherein (1)the distal ends of the fixed and movable jaws are at their maximumseparation due to interference of the spring itself, or (2) the distalends of the fixed and movable jaws are at their maximum separation dueto physical interference between portions of the fixed and movable jaws,or (3) the distal ends of the fixed and movable jaws are at theirmaximum separation due to other factors.

It is believed that ideally, the actuation force of the presentinvention should be at most about 9 pounds to facilitate easy opening ofthe jaws of the connector to its widest normal position. If theactuation force is above about 9 pounds, some users may have difficultyin using the connector, particularly those users who suffer from anailment such as arthritis which adversely affects their ability tosqueeze an object. Table 1 illustrates a the results of actuation forcetests run on the various connectors described above.

Tab Release Force Test

A test strip was created by providing a 3 mil (0.075 mm) thick strip ofpolyethylene terephthalate film 0.375 inches (0.94 cm) wide in themachine direction of the film by 2 inches (5 cm) long in the transversedirection of the film. The properties of the film included a tensilestrength of 28,000 psi in the machine direction, 35,000 psi in thetransverse direction, both as measured according to ASTM D882A. Thecoefficient of dynamic friction of this film was 0.5 as measured by ASTMD1894. The commercial source of this film was ICI Films of Wilmington,Del., branded as Melinex 505.

To this strip was laminated an adhesive tape composed of a backing oflow density polyethylene film having a hardness of 48 on the Shore Dscale according to ASTM 2240. The adhesive was a layer of 95.5%/4.5%isooctyl acrylate/acrylic acid copolymer adhesive, coated to a weight of920 mg/200 cm² of backing area. The total thickness of the finished tapewas 0.005 inches (0.12 mm) The commercial source of this tape was the 3MCompany, of St. Paul, Minn., branded as Blenderm tape. The totalthickness of the finished test strip was 0.008 inches.

A connector to be tested was used to grasp the test strip along thewidth axis, and was then clamped in the fixed jaw of an Instron forcetesting machine. The other end of the test strip was them clamped in themoving jaw of the machine, and the speed of the moving jaw was set to30.1 cm/minute. The peak force measured before the strip was pulled freeof the connector during tensile loading was measured.

It is believed that ideally, the tab release force of the presentinvention should be at least about 2 pounds. A tab release force ofabout 2 pounds is believed to be suitable for a wide variety of uses ofthe connector 10. If the tab release force is below about 2 pounds, thenit is believed that the tab of the electrode may be easily dislodgedfrom the connector, clearly a disadvantageous result. Table 1illustrates the results of tab release force tests run on the variousconnectors described above.

                  TABLE 1                                                         ______________________________________                                                   Tab Release Force                                                             (Pull-off Force)                                                                            Actuation Force                                      Connector  (Pounds)      (Pounds)                                             ______________________________________                                        Clip A     (3.9)          3.3                                                 (Present                                                                      Invention)                                                                    Clip B      (.5)          3.0                                                 Clip C     (1.3)          3.0                                                 Clip D      (.8)         10.2                                                 Clip E     (1.0)         12.5                                                 Clip F     (4.6)         28.3                                                 Clip G     (1.0)         11.6                                                 ______________________________________                                    

The present invention has now been described with reference to severalembodiments thereof. It will be apparent to those skilled in the artthat many changes or additions can be made in the embodiments describedwithout departing from the scope of the present invention. Thus, thescope of the present invention should not be limited to the structuresdescribed in this application, but only by structures described by thelanguage of the claims and the equivalents of those structures.

We claim:
 1. In combination, a biomedical electrode having anelectrically conductive contacting tab, said electrically conductivecontacting tab comprising a firm, flexible layer and a deformable layer;anda connector for said biomedical electrode, said connector comprising:a fixed jaw having a smooth, continuous tab engagement surface, amovable jaw having a manually engagable actuation surface and having apair of teeth defining a groove therebetween, each tooth having a tabengagement surface, pivotal mounting means for mounting the movable jawfor pivotal movement relative to the fixed jaw between a tab acceptposition with the fixed jaw spaced from the movable jaw so that the tabof the biomedical electrode may be received between the jaws, and aclosed position with the fixed and movable jaws spaced more closely thanin the tab accept position, wherein when the tab of the biomedicalelectrode is received between the jaws of the connector and the jaws arein the closed position, at least a portion of the deformable layer ofsaid electrically conductive contacting tab is received in said groove,and biasing means for biasing the movable jaw toward the closedposition.
 2. In combination, a biomedical electrode having anelectrically conductive contacting tab, said electrically conductivecontacting tab comprising a firm, flexible layer and a deformable layer;anda connector for said biomedical electrode, said connector comprising:a fixed jaw having a tab engagement surface, a movable jaw having amanually engagable actuation surface, one of the fixed or movable jawshaving a pair of teeth defining a groove therebetween, each tooth havinga tab engagement surface, and the other of the fixed or movable jawshaving a smooth, continuous tab engagement surface, pivotal mountingmeans for mounting the movable jaw for pivotal movement relative to thefixed jaw between a tab accept position with the fixed jaw spaced fromthe movable jaw so that the tab of the biomedical electrode may bereceived between the jaws, and a closed position with the fixed andmovable jaws spaced more closely than in the tab accept position,wherein when the tab of the biomedical electrode is received between thejaws of the connector and the jaws are in the closed position, at leasta portion of the deformable layer of said electrically conductivecontacting tab is received in said groove, and biasing means for biasingthe movable jaw toward the closed position.
 3. A method of using aconnector for biomedical electrodes comprising the steps of:(1)providing a biomedical electrode having an electrically conductivecontacting tab, said electrically conductive contacting tab comprising afirm, flexible layer and a deformable layer, and (2) providing theconnector for biomedical electrodes, said connector comprising:a fixedjaw having a tab engagement surface, a movable jaw having a manuallyengagable actuation surface, and one of the fixed or movable jaws havinga pair of teeth defining a groove therebetween, each tooth having a tabengagement surface, and the other of the fixed or movable jaws having asmooth, continuous tab engagement surface, (3) mounting the movable jawfor pivotal movement relative to the fixed jaw between a tab acceptposition with the fixed jaw spaced from the movable jaw so that the tabof the biomedical electrode may be received between the jaws, and aclosed position with the fixed and movable jaws spaced more closely thanin the tab accept position, (4) biasing the movable jaw toward theclosed position, and (5) placing the tab of the biomedical electrodebetween the jaws of the connector and allowing the jaws of the connectorto be biased toward the closed position so that at least a portion ofthe deformable layer of said electrically conductive contacting tab isreceived in said groove.